Transcript for Investigation Into This Week's Train Derailment Focuses on Engineer

Androgel 1.62%. Next tonight we keep hearing more about the role of fatigue and zoning out in that deadly train derailment right here in new york. So we wanted to know more about the issue of sleeping with your eyes wide open when you are behind the wheel of a car. Can it really happen? Here's abc's ron claiborne. Reporter: The investigation into this week's deadly train derailment, now focusing on this man, william rockefeller, the train's engineer. Sources telling abc news rockefeller admitted to "dozing off" right before the 82 mile per hour crash. It was a shock to him. He was stunned. He caught himself but he caught himself too late. Reporter: His lawyer says rockefeller felt well-rested earlier that morning and that he had succumbed not to sleep, but to something called "highway hypnosis" -- a kind of trance-like state usually associated with the boredom of long distance driving. People that often tell you they have been hypnotized by the highway are in fact, very sleepy. Reporter: Fatigue is a factor in many transportation accidents. The air disaster outside buffalo in 2009 blamed on pilot fatigue. On our roads, as many as 250,000 drivers nodding off every day. Look at this woman, caught on tape, seemingly fast asleep. Many victims of something called micro-sleep -- episodes of sleep as brief as a few seconds. Your eyes can be open, but your brain is asleep. Micro sleep is very brief from wakefulness to sleep. It can last anywhere from 20 to 30 seconds. Reporter: I found out first hand when I investigated the effect of sleep deprivation on driving -- staying awake for 30 hours, then getting behind the wheel on a test track while attached to a brain wave monitor and eye monitor. I thought I'd done kay, but my brain scans showed I'd dozed off 22 times -- without realizing it. Those jagged lines signaling sleep. You had dozens of times when your eyes began rolling around in their sockets. Reporter: The question investigators are trying to answer now, did lack of sleep play a roll. They are looking at fatigue as a possible factor. Again, his lawyer insists he felt fine, well rested, reported for work at 5:00 that sunday morning and keep in mind he made nine stops before that deadly crash. More than 20 times your brain waves show you were sleeping and you didn't know it. I did not remember any of those times and I was asleep for a second or two. It can happen. Real cautionary tale for everybody driving. Thank you so much, ron.

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